Open-File Report 2015–1059
The playa of the Dasht-e-Nawar basin, east-central Afghanistan, has historically been investigated for potential evaporate mineral deposits. In 2014, the U.S. Department of Defense Task Force for Business and Stability Operations contracted Centar American and SRK Consulting, Inc. to assess a potential lithium (Li) brine resource, conduct a basin gravity survey, and collect subsurface brines and sediments. The U.S. Geological Survey collaborated with this effort by providing analysis of Landsat imagery prior to, and during, field data collection; measurements of specific gravity of sediment and rock samples; oversight of passive seismic data collection and subsequent analysis; and an independent analysis of the chemistry and mineralogy of the subsurface samples. The Afghanistan Geological Survey collaborated by providing lithologic descriptions of subsurface sediment cores. This report presents the data collected and analyzed by the U.S. Geological Survey from June–September 2014, and the lithologic descriptions of sediment cores collected by the Afghanistan Geological Survey.
In September 2014, six boreholes were drilled in the dry lake surface of Dasht-e-Nawar basin. A total of 406 m of sediment core was collected, along with 44 pore-water samples. The longest core was 109 m, followed by 99 m, 63 m, and three 45 m cores. As of September 2014, pore waters from four of the six boreholes had been analyzed. Major cation concentrations were Na (3–1090 mg/L) > Mg (12.1–243 mg/L) > Ca (7.2–69.8 mg/L) > K (<0.05–59.9 mg/L). Lithium ranged from <50 to186 μg/L and did not show a consistent pattern with sample depth. This range is about three orders of magnitude less than Li concentrations in springs and brines of South America, where Li brines are mined.
Interpretation of the data from the passive seismic survey suggests that the maximum sediment thickness in the northern lobe of the basin is 107 m, and in the southern lobe of the basin it is 173 m. Although the boreholes did not extend to the basin floor, the low Li concentration observed in pore waters does not suggest the presence of a viable Li brine resource at Dasht-e-Nawar.
First posted May 4, 2015
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Stillings, L.L., Mack, T.J., Chornack, M.P., Kalaly, S.S., Ahmadi, M.I., and Akbar, A.Q., 2015, A summary of data collected by the U.S. Geological Survey at Dasht-e-Nawar, Afghanistan, in support of lithium exploration, June–September 2014: U.S. Geological Survey Open-File Report 2015–1059, 70 p., https://dx.doi.org/10.3133/ofr20151059.
ISSN 2331-1258 (online)